Department of Chemistry, Tokyo Institute of Technology, 2-12-1 O-okayama, Tokyo 152-8551, Japan.
Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
ACS Chem Biol. 2023 Apr 21;18(4):875-883. doi: 10.1021/acschembio.3c00011. Epub 2023 Mar 15.
Lyngbyapeptin B is a hybrid polyketide-nonribosomal peptide isolated from particular marine cyanobacteria. In this report, we carried out genome sequence analysis of a producer cyanobacterium to understand the biosynthetic mechanisms that generate the unique structural features of lyngbyapeptin B, including the ()-3-methoxy-2-butenoyl starter unit and the C-terminal thiazole moiety. We identified a putative lyngbyapeptin B biosynthetic () gene cluster comprising nine open reading frames that include two polyketide synthases (PKSs: LynB1 and LynB2), four nonribosomal peptide synthetases (NRPSs: LynB3, LynB4, LynB5, and LynB6), a putative nonheme diiron oxygenase (LynB7), a type II thioesterase (LynB8), and a hypothetical protein (LynB9). In vitro enzymatic analysis of LynB2 with methyltransferase (MT) and acyl carrier protein (ACP) domains revealed that the LynB2 MT domain (LynB2-MT) catalyzes O-methylation of the acetoacetyl-LynB2 ACP domain (LynB2-ACP) to yield ()-3-methoxy-2-butenoyl-LynB2-ACP. In addition, in vitro enzymatic analysis of LynB7 revealed that LynB7 catalyzes the oxidative decarboxylation of (4)-2-methyl-2-thiazoline-4-carboxylic acid to yield 2-methylthiazole in the presence of Fe and molecular oxygen. This result indicates that LynB7 is responsible for the last post-NRPS modification to give the C-terminal thiazole moiety in lyngbyapeptin B biosynthesis. Overall, we identified and characterized a new marine cyanobacterial hybrid PKS-NRPS biosynthetic gene cluster for lyngbyapeptin B production, revealing two unique enzymatic logics.
从特定的海洋蓝细菌中分离得到的 Lyngbyapeptin B 是一种混合的聚酮-非核糖体肽。在本报告中，我们对产生 Lyngbyapeptin B 的蓝细菌进行了基因组序列分析，以了解产生 Lyngbyapeptin B 独特结构特征的生物合成机制，包括（）-3-甲氧基-2-丁烯酰基起始单元和 C 端噻唑部分。我们鉴定了一个推定的 Lyngbyapeptin B 生物合成（）基因簇，该基因簇包含九个开放阅读框，其中包括两个聚酮合酶（PKS：LynB1 和 LynB2）、四个非核糖体肽合酶（NRPS：LynB3、LynB4、LynB5 和 LynB6）、一个假定的非血红素二铁加氧酶（LynB7）、一种 II 型硫酯酶（LynB8）和一个假设蛋白（LynB9）。体外酶分析表明，LynB2 中的甲基转移酶（MT）和酰基载体蛋白（ACP）结构域催化 LynB2-ACP 中乙酰乙酰基-LynB2-ACP 的 O-甲基化，生成（）-3-甲氧基-2-丁烯酰基-LynB2-ACP。此外，体外酶分析表明，LynB7 催化（4）-2-甲基-2-噻唑啉-4-羧酸在 Fe 和分子氧存在下发生氧化脱羧反应，生成 2-甲基噻唑。这一结果表明，LynB7 负责最后一个 NRPS 修饰，生成 Lyngbyapeptin B 生物合成中的 C 端噻唑部分。总之，我们鉴定并表征了一个新的海洋蓝细菌混合 PKS-NRPS 生物合成基因簇，用于 Lyngbyapeptin B 的生产，揭示了两种独特的酶学逻辑。
